CODEWITHSUNDEEP
c++polymorphism
Derf Skren
Derf Skren

Reputation: 509

Should I specify 'virtual' again when I override a C++ function?

When I override a virtual function:

class Geoff
{
 public:
  virtual int getArea() { return 0; }
}

Should I specify 'virtual' again when I override it? Does it make any difference? I know both ways seem to work fine, just wondering if there's more to it than that.

class George : public Geoff
{
 public:
  virtual int getArea() { return x*y; }
}

Upvotes: 17

Views: 1591

Answers (2)

Tony Delroy
Tony Delroy

Reputation: 106126

If you use C++11, you should use override instead, which both documents that you're overriding a virtual function and checks that a matching virtual function exists in a base for overriding.

int getArea() override { return x*y; }

In C++03 it's a stylistic choice - put virtual in if you feel it adds documentation value.

Upvotes: 26

Steven Sudit
Steven Sudit

Reputation: 19620

No, use override. (http://en.cppreference.com/w/cpp/language/override)

It has the advantage of failing if the method is not virtual in the parent.

edit

As Mark pointed out, it also fails if the signature doesn't match, whereas virtual would silently "succeed". The scare quotes are because a mismatched signature would hide the shadowed method in the base and make a new virtual method that's unrelated.

Upvotes: 7

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